Multicell Cluster

• Most common type of storm

• Groups of individual cells moving as one unit

• Each cell last 20 minutes, but cluster can last for hours

• Heavy rain is the main problem; winds, hail and weak tornadoes possible.

Decorative Image: An example of a multicell cluster storm Decorative Image: Diagram of multicell thunderstorm.

Speaker Notes:

• The next step up, in terms of severity, of thunderstorm types is the multi-cell cluster storms. These are the most common storms in our area.

• Multi-cell cluster storms contain several single cell storms. Some cells are in the developing stage, some are in the mature stage, and some are dissipating.

• Because there are several cells organized as a unit, the multi-cell clusters storms last much longer than single cell storms and cover a larger area.

• The biggest severe weather concern with multi-cell storms is when they move like a train over a train track dropping rain over the same area. We call these ‘training echoes’ which the next slide illustrates.

• In addition to flooding, high winds (non-tornadic), and hail are also possible. Very rarely, a weak tornado may develop under the leading edge of the downdraft called a ‘gustnado’. Gustnadoes will be discussed later.